For me there┤s a big difference between being able to/using your powers to raise people from their graves like zombies and giving people unnatural long life, so that they do not actually die, but pass into a shadow world between life and death. Tolkien writes in one of his letters that the Nazgűl do not have great physical powers, their powers reside in the unreasoning fear they inspire, like ghosts.

Zombies as they┤ve been described and portrayed in films and literature seem to me far too literal to resemble Tolkien┤s descriptions of the effects and nature of Sauron┤s magic (or The Witch King┤s magic).

Judging by your quote, it seems to me that Sauron played on the fear of death among the Numenˇreans, creating a cult of rituals, sacrifices and sorcery intended to deceive the Numenˇreans into thinking they actually could and even had the right to escape death and prolong their lives beyond their natural span.